This invention relates to the catalytic hydroprocessing of heavy hydrocarbon oils including crude oils, heavy crude oils and residual oils as well as refractory heavy distillates, including FCC decanted oils and lubricating oils. It also relates to the hydroprocessing of shale oils, oils from tar sands, and liquids derived from coals. The invention relates to a catalyst for the hydroprocessing of such hydrocarbonaceous feedstocks, the use of such catalysts, and the preparation of such catalysts.
In U.S. Ser. No. 527,414 filed Aug. 29,1983 (now U.S. Pat. No. 4,557,821), a parent application of the present application, a catalytic means of hydroprocessing heavy oils was revealed which employs a circulating slurry catalyst. The catalyst comprised a dispersed form of molybdenum disulfide prepared by reacting aqueous ammonia and molybdenum oxide to form an aqueous ammonium molybdate which was reacted with hydrogen sulfide to form a precursor slurry. The precursor slurry was mixed with feed oil, hydrogen and hydrogen sulfide and heated under certain conditions. A variety of dosages of hydrogen sulfide expressed as SCF of hydrogen sulfide per pound of molybdenum were taught to be useful in forming the precursor slurry (Column 3). From 2-8 SCF/LB were preferred (Column 4). It was found to be necessary to mix the slurry with oil in the presence of both hydrogen and hydrogen sulfide in order to obtain a catalytically active slurry catalyst (Columns 11-12). The oil-slurry mixture was then sulfided with hydrogen and hydrogen sulfide at at least two temperatures (Column 24) under certain conditions. The feed and catalyst, with water added were charged to the hydroprocessing reactor. Water introduction was deemed beneficial (Columns 26-27) for certain purposes, as was nickel addition to the slurry catalyst (Columns 42-44).
In U.S. Ser. No. 941,456 filed Dec. 15, 1986 (U.S. Pat. No. 4,857,496), a parent application of the present application, is described a sulfiding process in which there are two or three heating steps providing time-temperature sequences to complete the preparation of the final catalyst prior to flowing the feed to the higher temperature hydroprocessing reactor zone. Each sulfiding step was operated at a temperature higher than its predecessor. Ammonia was removed from an intermediate stage of catalyst preparation before the addition of feed oil and further sulfiding.
U.S. Ser. No. 767,760 filed Aug. 21, 1985 (U.S. Pat. No. 4,824,821) also a continuation-in-part of U.S. Ser. No. 527,414 filed Aug. 29, 1983 describes the promotion of a Group VIB slurry catalyst by the addition of a Group VIII metal such as nickel, or cobalt, to the aqueous ammonia compound after sulfiding is underway.
U.S. Ser. No. 767,768 filed Aug. 21, 1985 (U.S. Pat. No. 4,710,486) also a continuation-in-part of U.S. Ser. No. 527,414 filed Aug. 29, 1983 describes the specific regulation of the amount of sulfiding occurring in intermediate temperature sulfiding steps by stoichiometric replacement of oxygen associated with the Group VIB metal with sulfur up to fifty to ninety-five percent replacement. At least three stages of sulfiding were preferred with additional replacement of oxygen by sulfur in the high temperature step.
U.S. Ser. No. 767,821 filed Aug. 21, 1985 (U.S. Pat. No. 4,762,812) also a continuation-in-part of U.S. Ser. No. 527,414 filed Aug. 29, 1983 described a process for the recovery of spent molybdenum catalysts.
A parent application of the present application U.S. Ser. No. 275,235 filed Nov. 22, 1988 described a Group VIB metal sulfide slurry catalyst for hydroprocessing heavy oils or residual oil which has a pore volume in the 10-300 angstrom radius pore size range of at least 0.1 cc/g.
In U.S. Pat. No. 4,376,037 and U.S. Pat. No. 4,389,301 a heavy oil is hydrogenated in one or two stages by contacting the oil with hydrogen in the presence of added dispersed hydrogenation catalysts suspended in the oil, as well as in the additional presence of porous solid contact particles. In the two-stage version, the normally liquid product of the first stage is hydrogenated in a catalytic hydrogenation reactor. The dispersed catalyst can be added as an oil/water emulsion prepared by dispersing a water-soluble salt of one or more transition elements in oil. The porous contact particles are preferably inexpensive materials such as alumina, porous silica gel, and naturally occurring or treated clays. Examples of suitable transition metal compounds include (NH.sub.4).sub.2 MoO.sub.4, ammonium heptamolybdate and oxides and sulfides of iron, cobalt and nickel. The second reaction zone preferably contains a packed or fixed bed of catalysts, and the entire feed to the second reaction zone preferably passes upwardly through the second zone.
In U.S. Pat. No. 4,564,439 a heavy oil is converted to transportation fuel in a two-stage, close-coupled process, wherein the first stage is a hydrothermal treatment zone for the feed-stock mixed with dispersed demetalizing contact particles having coke-suppressing activity, and hydrogen; and the second stage closely coupled to the first, is a hydrocatalytic processing reactor.
The specifications of all of the foregoing U.S. patents and applications are incorporated herein by reference as if fully set forth in ipsis verbis.
Increasingly, petroleum refiners find a need to make use of heavier or poorer quality crude feedstocks in their processing. As that need increases the need also grows to process the fractions of those poorer feedstocks boiling at elevated temperatures, particularly those temperatures above 1000.degree. F., and containing increasingly high levels of contaminants, such as undesirable metals, sulfur, and coke-forming precursors. These contaminants significantly interfere with the hydroprocessing of these heavier fractions by ordinary hydroprocessing means. The most common metal contaminants found in these hydrocarbon fractions include nickel, vanadium, and iron. The various metals deposit themselves on hydrocracking catalysts, tending to poison or de-activate those catalysts. Additionally, metals and asphaltenes, and coke-precursors can cause interstitial plugging of catalyst beds, reduce catalyst life, and run length. Moreover, asphaltenes also tend to reduce the susceptibility of hydrocarbons to desulfurization processes. Such de-activated or plugged catalyst beds are subject to premature replacement.
It would be advantageous to cure these problems with the least upset to conventional processing techniques and at the lowest cost. If, for example, dispersed, consumable catalysts are used, the catalyst should be effective at the lowest possible concentration to reduce the cost of catalytic treatment.
As a practical matter the run length and fixed bed resid desulfurization process is limited by coke and/or metals loadings of the catalyst. Improved fixed bed performance, catalyst life and improved 1000.degree. F.+ conversions can be obtained by reducing the levels of metals and coke precursors which plug the pores and/or penetrate the catalyst pore volume containing active catalytic sites. The prior art teaches that the extension of run length in fixed bed resid desulfurization processes can be achieved by: increasing the size of the reactor; decreasing the feed rate; the use of macro-porous demetalation catalyst, especially in the top of the beds; or by the employment of either catalyst charging methods and/or operating procedures which distribute the metals evenly along the bed. Because demetalation is both a function of the metals content of the feedstock and the processing temperature, metals loading of fixed bed catalysts can be controlled by varying both catalyst activity and temperature along the reactor's length. Uniform axial metal deposition can be accomplished through the use catalyst beds which are graded by activity or by imposing temperature profiles in the bed which yield uniform metal deposition.
For the processing of heavy oils characterized by low hydrogen to carbon ratios (i.e. less than about 1/8 by weight) and high carbon residues, asphaltenes, nitrogen, sulfur and metal contaminant contents, it would be advantageous if the parameters for the preparation of a high activity slurry catalyst were known.
It would also be advantageous if the performance of existing fixed bed reactors could be increased by the use of slurry catalysts.